Process for distilling formic acid.



A. BRUER. PROCESS FOR GISTILLING FORMIC ACID.

APPHCAHON FILED 0CT.!.1915.

Patentcd Mar. 7,-1916.

mmm? BEUEE, 03:* GRNT, NEAR .EE1LIN, SSIGTOR TO CHEMISCHE FABEIK-- GE'NAU LAIDSHOFF & EEYER XTENGESELLSCHAFT. CF GNU,

PECESS ECB. JSTIJL'IG FGE AC'IIl En ei'ecti'ig istiiiatin by iii& prec atit germi-1111)" inseithe stili which is pfl'fii With strong agitakg is charged With u quantitjy-'ofithe mixture. of ''eaction acciarding ta) its'c'api'cty the formic aci'' driven si? iri a vaciiiir' QI' %vinit-:ins ef ai perceiitage Gf'f'fi cid intim mixture dilninishes, untii it becomes &lower by degrees'an can only be finished in a vacuum m' 'oj means of a circuiatiig.current of air. 'It was not possible; to overcome this undesirabie cieia fin' the istiiiinz process by any means,'becaise itdie to the increase in the 'mik of the snl'fate 'in th& mass* to be dis killed which 'thu is converted inte a thick paste. in: spite of .vigomus figli-&timi thef thic'- pasta'coverstbe heating agimi-.tashi dead weight anti caises agreat cmszmp'sion of power and heat, 'untii the distiiaion is finishd. t has 't''eenmzid by experience that the drivin'g off of the'iasbthd of the 'mtai formicicid-in the cimrg ta ime (iistilled requires about two thirds of the time necessry for the, whoie disiiiation. I

I have found that the ditinaticn can be efl'ected ichmorc quickly andwith a gveat saving cost for Tzhof, whiie the drawhacks mentikmeii aimve can nisu be avcided if the mixture of formate and snif zric seid' i is placed on a snrface-eviporator in a. thin layer. The mixure may' 'iii: plad on a 'ne ted %ndy of rmmd'shape, fin? insianc a I'Otfltif heatad milet ai' a" him, v the :19 1 been driven off 'iha .cif e i once scraped o This can be done contiin Specificsn of Letters Patezt.

add, Simi& time, s

.consists in the possibiiity ef inci-ensing the,

& atent-, i

1915. Serial Ho. 233.334.

%127. Lio.

ces

90 ticniy ncesat'ft drin i t s -f'afan the specificaiiy heavy vapor of {di-miq &Cid und todrive them to the condsii 'g' appamts. By. these. means tliej 'ieid (f the. finished acid is some-,what izcregse& because the pGducc-d by' thi: di'stillzion 'mmm are entirely .liminutc 4 A furi-her advantage of my nmgci process output 'of strong formiq acid which i'esnlt {mm the heating suri' ce being completely niiized. Caiculuted (in tiu\ unit f surface, i have 'found that I cam distiil fmin 9 to 3 times "111911 fnrmic ;icin in the. same time as with the od system nf disiiutinn in a stiii Tim' greatest advantage..luwm'ex iies costs of labor, repairs and general expenses are distributed over a greatly increased output and the space taken up by the heated rollers and appurtenances' with the equal Capacity of production is only a fraction of the old apparatus. The costs of the plant are also greatly diminished.

Finally it should be noted that distillation according to the present process can be interrupted at any moment and can be controlled at will, which is not possible with the old app-aratus.

A -further, improvement consists in the continuous separation of the sulfate in closed chamber, whereby the liberation of the strongly acid vapos, so very danaging to the health of the* workmen, is totally prevented.

A diagramnatic representation of an apparatus suitable for carrying out my novel process is shown in the accompanying drawing, in which i Figure 1. is a vertical section and Fig. 2 a plan. I i i i Into a closed eha nb l; A' is placed a box K into which al l abl' drum T is dipped insch a'mannerg t at as the drum rotates it is covered with a thinlayer of the mixture of formate and sulm -grafia whichis'continuously fed- 'into the x l by' means of a pipe R.` By the heat aqueousvapors of for nic a'cid are at once liberated-whi'ch escape through the pipe E and are carri'ed to a con- '-de`nse r (not shown), while the solid residue on the drum is'scraped off bye kriife M and falls into a ear W.'

It 'will be understood that the specific apparatus illustrate'd and described is merely illustrative, and that my'process is not limited to the use of any particular kind of apparatus. The construction of the latter may be varied to suit the requirements of any given occasion.

What I claim is 1- 1. A process for distilling formie acid,consisting in* covering a 'heated rotating sur face-evaporato` with a mixture of a formate and sulfuric acid in a thin layer, whereupon the solid residue is scraped off after the liberation of the for-mie acid vapors and the evaporation of the mass. has taken place, before a new supply of the mixture is brought onto the surface of the rotating evaporator, substantially as'described.

2. A process for distilling fol-mic acid,

a. thin layer of a nixture of a formate :in sul-` furic acid to an evaporating surface, drivin'g otl' the formic acid vapors'by heat, and removing the solid residue frm the evaporating surface.

In testimony whereof I afiix my signature in presence of two witnesses.

i ADOLF BRUER.

Witnesses l/VoLDEMAn HAUPT, HENRY HAsrER. 

